A conventional redundant power system usually consists of multiple sets of power supplies that share a common chassis. Namely the power supplies have a common housing and a power integration back panel for control. In practice, it is called an N+M structure, where N is the number of power supplies to be clustered to meet total loading requirement of industrial computers, and M is the number of the power supplies allowed to be disabled. Take 2+1 structure as an example. It consists of three sets of power supplies. The 1 at the rear means that one power supply may be disabled while other power supplies can still provide regular power needed. Depending on different requirements, an N+2 structure may also be adopted.
R.O.C. patent publication No. 562163 entitled “Redundant power supply” has a housing 10 and more than one track room 14 inside to position more than one power supply 30 connecting to a plurality of connectors 12 on a circuit board 11. The circuit board 11 integrates output power of the power supplies 30 to form a redundant power supply.
The circuit board 11 previously discussed is the “back panel” commonly called in the redundant power supply. It mainly aims to integrate the power of multiple power supplies and also transform the power to supply output power of more than one different potential. To meet the prevailing trend that demands slim and light, the redundant power system also has to be made compact. Hence the individual power supplies have to be made smaller, and the back panel also has to be shrunk. Such a demand creates problems in practice, notably:
First, to shrink the circuit board is difficult. As the back panel has to provide two basic functions of power integration and transformation, significant amount of power and current are converged on the back panel. Hence a sufficient insulation capability has to be provided to meet safety regulations. Shrinking the size generally reduces the insulation capability, and voltage-resistance and insulation specifications of circuit elements also have to be enhanced. All this makes design more difficult and cost higher.
Second, heat dissipation also is more difficult. Given the same amount of current and power integration and transformation, heat dissipation on the smaller back panel is more difficult. Moreover, the dimensions of electronic elements for a greater current also are larger, hence the heat dissipation space for airflow is smaller. The smaller back panel has a higher power density in a unit area and a smaller area in contact with the air, and results in poorer heat dissipation of elements. As a result, malfunction probability increases.